Figure 15.1: We get most of our energy by burning carbon-containing fossil fuels (see Figure 2-14, p. 46). This figure shows energy use by source throughout the world (left) and in the United States (right) in 2008. Note that oil is the most widely use form of commercial energy and that about 79% of the energy used in the world (85% of the energy used the United States) comes from burning nonrenewable fossil fuels. (These figures also include rough estimates of energy from biomass that is collected and used by individuals without being sold in the marketplace.) Question: Why do you think the world as a whole relies more on renewable energy than the United States does? (Data from U.S. Department of Energy, British Petroleum, Worldwatch Institute, and International Energy Agency )
Figure 15.2: We can pump oil up from underground reservoirs on land (left) and under the sea bottom (right). Today, high-tech equipment can tap into an oil deposit on land and at sea to a depth of almost 11 kilometers (7 miles). But this requires a huge amount of high-quality energy and can cost billions of dollars per well. For example, the well that tapped into BP’s Thunder Horse oil field in the Gulf of Mexico at water depths of up to 1.8 kilometers (1.1 miles) took almost 20 years to complete and cost more than $5 billion. And as we saw in 2010 with the explosion of a BP deep-sea oil-drilling rig such as that shown here, there is a lot of room for improvement in deep-sea drilling technology.
Figure 15.3: S cience. Net energy ratios for various energy systems over their estimated lifetimes differ widely: the higher the net energy ratio, the greater the net energy available ( Concept 15-1 ). Question: Based on these data, which two resources in each category should we be using? (Data from U.S. Department of Energy; U.S. Department of Agriculture; Colorado Energy Research Institute, Net Energy Analysis , 1976; and Howard T. Odum and Elisabeth C. Odum, Energy Basis for Man and Nature , 3rd ed., New York: McGraw-Hill, 198 1)
Figure 15.4: S cience. When crude oil is refined, many of its components are removed at various levels, depending on their boiling points, of a giant distillation column (left) that can be as tall as a nine-story building. The most volatile components with the lowest boiling points are removed at the top of the column. The photo above shows an oil refinery in the U.S. state of Texas .
Figure 15.5: The amount of crude oil that might be found in the Arctic National Wildlife Refuge (right), if developed and extracted over 50 years, is only a tiny fraction of projected U.S. oil consumption. In 2008, the DOE projected that developing this oil supply would take 10–20 years and would lower gasoline prices at the pump by 6 cents per gallon at most. (Data from U.S. Department of Energy, U.S. Geological Survey, and Natural Resources Defense Counc il)
Figure 15.6: Using crude oil as an energy resource has advantages and disadvantages ( Concept 15-2a ). Questions: Which single advantage and which single disadvantage do you think are the most important? Why?
Figure 15.7: This bird was covered with oil from an oil spill in Brazilian waters. If volunteers had not removed the oil, it would have destroyed this bird’s natural buoyancy and heat insulation, causing it to drown or die from exposure because of a loss of body heat.
Figure 15.8: Producing heavy oil from Canada’s Alberta tar sands project involves strip-mining areas large enough to be seen from outer space, draining wetlands, and diverting rivers. It also produces huge amounts of air and water pollution and has been called the world’s most environmentally destructive project. For oil from the sands to be profitable, oil must sell for $70–90 a barrel.
Figure 15.9: Shale oil (right) can be extracted from oil shale rock (left). However, producing shale oil requires large amounts of water and has a low net energy yield and a very high environmental impact.
Figure 15.11: Natural gas found above a deep sea oil well deposit or in a remote land area is usually burned off (flared) because no pipeline is available to collect and transmit the gas to users. This practice wastes this energy resource and adds climate-changing CO 2 , soot, and other air pollutants to the atmosphere. Question: Can you think of an alternative to burning off this gas?
Figure 15.12: Using conventional natural gas as an energy resource has advantages and disadvantages ( Concept 15-3 ). Questions: Which single advantage and which single disadvantage do you think are the most important? Why? Do you think that the advantages of using conventional natural gas outweigh its disadvantages?
Figure 15.13: Gas hydrates are crystalline solids that can be burned as shown here. They form naturally from the reaction of various gases (commonly methane) with water at low temperatures and under high pressures. Natural gas hydrates form extensively in permafrost and in sediments just under the sea floors around all of the world’s continents. Methane hydrates, shown here, are a potentially good fuel.
Figure 15.16: This coal-burning industrial plant in India produces large amounts of air pollution because i t has inadequate air pollution controls.
Figure 15.17: CO 2 emissions, expressed as percentages of emissions released by burning coal directly, vary with different energy resources. Question: Which produces more CO 2 emissions per kilogram, burning coal to heat a house or heating with electricity generated by coal? (Data from U.S. Department of Energy )
Figure 15.18: Using coal as an energy resource has advantages and disadvantages ( Concept 15-4a ). Questions: Which single advantage and which single disadvantage do you think are the most important? Why? Do you think that the advantages of using coal as an energy resource outweigh its disadvantages?
Figure 2.9: There are three types of nuclear changes: natural radioactive decay (top), nuclear fission (middle), and nuclear fusion (bottom).
Figure 15.22: Using the nuclear power fuel cycle (Figure 15-21) to produce electricity has advantages and disadvantages ( Concept 15-5 ). Questions: Which single advantage and which single disadvantage do you think are the most important? Why? Do you think that the advantages of using the conventional nuclear power fuel cycle to produce electricity outweigh its disadvantages? Explain.
Figure 15.24: S cience. After 3 or 4 years in a reactor, spent fuel rods are removed and stored in a deep pool of water contained in a steel-lined concrete basin (left) for cooling. After about 5 years of cooling, the fuel rods can be stored upright on concrete pads (right) in sealed dry-storage casks made of heat-resistant metal alloys and concrete. Questions: Would you be willing to live within a block or two of these casks or have them transported through the area where you live in the event that they were transferred to a long-term storage site? Explain. What are the alternatives?
Figure 2.9: There are three types of nuclear changes: natural radioactive decay (top), nuclear fission (middle), and nuclear fusion (bottom).
Bio 105 Chapter 15
MILLER/SPOOLMAN LIVING IN THE ENVIRONMENT 17TH Chapter 15 Nonrenewable Energy
Energy Use: World and United States Fig. 15-1, p. 370
Basic Science: Net Energy Is the Only Energy That Really Counts (1)• First law of thermodynamics: • It takes high-quality energy to get high-quality energy • Pumping oil from ground, refining it, transporting it• Second law of thermodynamics • Some high-quality energy is wasted at every step
Basic Science: Net Energy Is the Only Energy That Really Counts (2)• Net energy • Total amount of useful energy available from a resource minus the energy needed to make the energy available to consumers• Net energy ratio: ratio of energy produced to energy used to produce it• Conventional oil: high net energy ratio
It Takes Energy to Pump Petroleum Fig. 15-2, p. 372
Energy Resources With Low/Negative Net Energy Yields Need Marketplace Help• Cannot compete in open markets with alternatives that have higher net energy yields• Need subsidies from taxpayers• Nuclear power as an example
Reducing Energy Waste Improves Net Energy Yields and Can Save Money• 84% of all commercial energy used in the U.S. is wasted • 43% after accounting for second law of thermodynamics• Drive efficient cars, not gas guzzlers• Make buildings energy efficient
We Depend Heavily on Oil (1)• Petroleum, or crude oil: conventional, or light oil• Fossil fuels: crude oil and natural gas• Peak production: time after which production from a well declines
We Depend Heavily on Oil (2)• Oil extraction and refining • By boiling point temperature• Petrochemicals: • Products of oil distillation • Raw materials for industrial organic chemicals • Pesticides • Paints • Plastics
How Long Might Supplies of Conventional Crude Oil Last? (1) • Rapid increase since 1950 • Largest consumers in 2009 • United States, 23% • China, 8% • Japan, 6%
How Long Might Supplies of Conventional Crude Oil Last? (2) • Proven oil reserves • Identified deposits that can be extracted profitably with current technology • Unproven reserves • Probable reserves: 50% chance of recovery • Possible reserves: 10-40% chance of recovery • Proven and unproven reserves will be 80% depleted sometime between 2050 and 2100
World Oil Consumption, 1950-2009 Figure 1, Supplement 2
Crude Oil in the Arctic National Wildlife Refuge Fig. 15-5, p. 376
The United States Uses Much More Oil Than It Produces• Produces 9% of the world’s oil and uses 23% of world’s oil• 1.5% of world’s proven oil reserves• Imports 52% of its oil• Should we look for more oil reserves? • Extremely difficult • Expensive and financially risky
U.S. Energy Consumption by Fuel Figure 6, Supplement 9
Proven and Unproven Reserves of Fossil Fuels in North America Figure 18, Supplement 8
Trade-Offs: Conventional Oil Fig. 15-6, p. 377
Bird Covered with Oil from an Oil Spill in Brazilian Waters Fig. 15-7, p. 377
Case Study: Heavy Oil from Tar Sand• Oil sand, tar sand contains bitumen• Canada and Venezuela: oil sands have more oil than in Saudi Arabia• Extraction • Serious environmental impact before strip-mining • Low net energy yield: Is it cost effective?
Strip Mining for Tar Sands in Alberta Fig. 15-8, p. 378
Will Heavy Oil from Oil Shales Be a Useful Resource? • Oil shales contain kerogen • After distillation: shale oil • 72% of the world’s reserve is in arid areas of western United States • Locked up in rock • Lack of water needed for extraction and processing • Low net energy yield
Oil Shale Rock and the Shale Oil Extracted from It Fig. 15-9, p. 379
Natural Gas Is a Useful and Clean-Burning Fossil Fuel • Natural gas: mixture of gases • 50-90% is methane -- CH4 • Conventional natural gas • Sits above oil
Natural Gas Burned Off at Deep Sea Oil Well Fig. 15-11, p. 380
Is Unconventional Natural Gas the Answer? • Coal bed methane gas • In coal beds near the earth’s surface • In shale beds • High environmental impacts or extraction • Methane hydrate • Trapped in icy water • In permafrost environments • On ocean floor • Costs of extraction currently too high
Trade-Offs: Conventional Natural Gas Fig. 15-12, p. 381
Coal Is a Plentiful but Dirty Fuel (1)• Coal: solid fossil fuel• Burned in power plants; generates 42% of the world’s electricity • Inefficient• Three largest coal-burning countries • China • United States • Canada
Coal Is a Plentiful but Dirty Fuel (2)• World’s most abundant fossil fuel • U.S. has 28% of proven reserves• Environmental costs of burning coal • Severe air pollution • Sulfur released as SO2 • Large amount of soot • CO2 • Trace amounts of Hg and radioactive materials
Air Pollution from a Coal-Burning Industrial Plant in India Fig. 15-16, p. 383
CO2 Emissions Per Unit of Electrical Energy Produced for Energy Sources Fig. 15-17, p. 383
World Coal and Natural Gas Consumption, 1950-2009 Figure 7, Supplement 9
Coal Consumption in China and the United States, 1980-2008 Figure 8, Supplement 9
Coal Deposits in the United States Figure 19, Supplement 8
The Clean Coal and Anti-Coal Campaigns• Coal companies and energy companies fought • Classifying carbon dioxide as a pollutant • Classifying coal ash as hazardous waste • Air pollution standards for emissions• 2008 clean coal campaign • But no such thing as clean coal
How Does a Nuclear Fission Reactor Work? (1)• Controlled nuclear fission reaction in a reactor • Very inefficient• Fueled by uranium ore and packed as pellets in fuel rods and fuel assemblies• Control rods absorb neutrons
How Does a Nuclear Fission Reactor Work? (2)• Water is the usual coolant• Containment shell around the core for protection• Water-filled pools or dry casks for storage of radioactive spent fuel rod assemblies
What Happened to Nuclear Power?• Slowest-growing energy source and expected to decline more• Why? • Economics • Poor management • Low net yield of energy of the nuclear fuel cycle • Safety concerns • Need for greater government subsidies • Concerns of transporting uranium
Global Energy Capacity of Nuclear Power Plants Figure 10, Supplement 9
Nuclear Power Plants in the United States Figure 21, Supplement 8
Case Study: Chernobyl: The World’s Worst Nuclear Power Plant Accident • Chernobyl • April 26, 1986 • In Chernobyl, Ukraine • Series of explosions caused the roof of a reactor building to blow off • Partial meltdown and fire for 10 days • Huge radioactive cloud spread over many countries and eventually the world • 350,000 people left their homes • Effects on human health, water supply, and agriculture
Trade-Offs: Conventional Nuclear Fuel Cycle Fig. 15-22, p. 389
Storing Spent Radioactive Fuel Rods Presents Risks• Rods must be replaced every 3-4 years• Cooled in water-filled pools• Placed in dry casks• Must be stored for thousands of years• Vulnerable to terrorist attack
Dealing with Spent Fuel Rods Fig. 15-24, p. 390
Dealing with Radioactive Wastes Produced by Nuclear Power Is a Difficult Problem • High-level radioactive wastes • Must be stored safely for 10,000–240,000 years • Where to store it • Deep burial: safest and cheapest option • Would any method of burial last long enough? • There is still no facility • Shooting it into space is too dangerous
What Do We Do with Worn-Out Nuclear Power Plants?• Decommission or retire the power plant• Some options 1. Dismantle the plant and safely store the radioactive materials 2. Enclose the plant behind a physical barrier with full-time security until a storage facility has been built 3. Enclose the plant in a tomb • Monitor this for thousands of years
Can Nuclear Power Lessen Dependence on Imported Oil & Reduce Global Warming?• Nuclear power plants: no CO2 emission• Nuclear fuel cycle: emits CO2• Need high rate of building new plants, plus a storage facility for radioactive wastes
Will Nuclear Fusion Save Us?• “Nuclear fusion • Fuse lighter elements into heavier elements • No risk of meltdown or large radioactivity release• Still in the laboratory phase after 50 years of research and $34 billion dollars• 2006: U.S., China, Russia, Japan, South Korea, and European Union • Will build a large-scale experimental nuclear fusion reactor by 2018
Experts Disagree about the Future of Nuclear Power• Proponents of nuclear power • Fund more research and development • Pilot-plant testing of potentially cheaper and safer reactors• Opponents of nuclear power • Fund rapid development of energy efficient and renewable energy resources
Three Big Ideas1. A key factor to consider in evaluating the usefulness of any energy resource is its net energy yield.2. Conventional oil, natural gas, and coal are plentiful and have moderate to high net energy yields, but using any fossil fuel, especially coal, has a high environmental impact.3. Nuclear power has a low environmental impact and a very low accident risk, but high costs, a low net energy yield, long-lived radioactive wastes, and the potential for spreading nuclear weapons technology have limited its use.